A so-called “cooling/heating free type air conditioner,” which is an indoor-multi-type air conditioner that includes a plurality of indoor units connected in parallel with an outdoor unit and is able to perform a cooling operation and a heating operation in parallel with each other, has been known (see, e.g., Patent Document 1). Patent Document 1 discloses upgrading a preinstalled indoor-multi-type air conditioner that performs either a cooling operation or a heating operation just selectively, not in parallel with each other, to the cooling/heating free type air conditioner.
The air conditioner of Patent Document 1 is configured by upgrading an air conditioner (1A) in which an outdoor unit (2) is connected with a plurality of indoor units (3) through two communication pipes (11, 12, 13, 14) to make a switch from cooling to heating, and vice versa, as illustrated in FIG. 3 into an air conditioner including a cooling/heating switching unit (6) so that the indoor units (3) are connected in parallel with the cooling/heating switching unit (6) as illustrated in FIG. 5. In this configuration, the cooling/heating switching unit (6) changes flow directions of refrigerants for the indoor units (3) so that a cooling operation and a heating operation can be performed in parallel with each other.